© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
273
This peripheral is available in LPC2142/4/6/8 devices.
18.1 Features
•
10 bit digital to analog converter
•
Resistor string architecture
•
Buffered output
•
Power-down mode
•
Selectable speed vs. power
18.2 Pin description
gives a brief summary of each of DAC related pins.
18.3 DAC Register (DACR - 0xE006 C000)
This read/write register includes the digital value to be converted to analog, and a bit that
trades off performance vs. power. Bits 5:0 are reserved for future, higher-resolution D/A
converters.
UM10139
Chapter 18: Digital-to-Analog Converter (DAC)
Rev. 01 — 15 August 2005
User manual
Table 261: DAC pin description
Pin
Type
Description
AOUT
Output
Analog Output. After the selected settling time after the DACR is
written with a new value, the voltage on this pin (with respect to
V
SSA
) is VALUE/1024 * V
REF
.
V
REF
Reference
Voltage Reference. This pin provides a voltage reference level for
the D/A converter.
V
DDA
, V
SSA
Power
Analog Power and Ground. These should be nominally the same
voltages as V
3
and V
SSD
, but should be isolated to minimize noise
and error.
Table 262: DAC Register (DACR - address 0xE006 C000) bit description
Bit
Symbol Value
Description
Reset
value
5:0
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA
15:6
VALUE
After the selected settling time after this field is written with a
new VALUE, the voltage on the A
OUT
pin (with respect to V
SSA
)
is VALUE/1024 * V
REF
.
0
16
BIAS
0
The settling time of the DAC is 1
µ
s max, and the maximum
current is 700
υ
A.
0
1
The settling time of the DAC is 2.5
µ
s and the maximum
current is 350
µ
A.
31:17 -
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA